Abstract

Narrow spectral linewidth semiconductor lasers are essential in optical coherent communication systems. We have previously reported a 170-kHz linewidth [1] achieved by introducing corrugation-pitch-modulated (CPM) gratings into 1.2-mm-Iong multi-quantum-well distributed feedback (MQW-DFB) lasers. Rebroadening of spectral linewidth was not observed in CPM-MQW-DFB lasers, and their spectral linewidth tended to saturate at high output powers. Here we report the power spectral density of FM noise of a CPM-MQW-DFB laser to clarify the saturation mechanism of spectral linewidth, and 56-kHz spectral linewidth obtained by reducing the parasitic FM noise.

© 1991 Optical Society of America